China sharply criticized the U.S. for its plan to sell Taiwan more than $1 billion-worth of weapons.

Beijing called it the “wrong decision,” which threatens the goodwill between both countries following the April summit between Presidents Xi and Trump.

CGTN’s Owen Fairclough has more.

China’s President Xi Jinping and Donald Trump opening a new chapter at their first meeting on a crucial but sometimes fractious relationship—a joint pledge to work together on tough trade and geopolitical issues.

Nearly three months on and the mood has soured after Trump’s decision to sell Taiwan $1.4 billion-worth of weapons.

“Taiwan is an integral part of Chinese territory, the arms sales by the United States seriously violates international law, basic norms governing international relations, the Three Joint Communiques between China and the U.S., and harm China national sovereignty and security interests,” said Lu Kang of the Chinese Foreign Ministry. “China resolutely opposes this.”

The deal is small compared to previous weapons deals with Taiwan. However, it’s the first of its kind under Trump and hugely sensitive on the issue of Chinese sovereignty.

Washington has a longstanding commitment to help Taipei maintain its defense capabilities and doesn’t think it overstepped the mark.

“I should point out, to our longstanding one-China policy, which is based – as you all know – on three joint communiqués on the Taiwan Relations Act. There is continuity here,” Heather Nauert of the U.S. State Department said. “The United States has been doing defense sales with Taiwan for 50 years or so.”

However, suggestions this deal with help promote regional stability were given short shrift by China’s man in Washington.

“How can you promote peace and stability by selling arms? This is a most ridiculous argument,” Cui Tiankai, Chinese Ambassador to the U.S. said.

Just how much this deal will harm the relations will likely to be tested when Xi and Trump are expected to meet at the G20 summit in Germany next week.